The present invention relates generally to tracking systems for tracking the location of valuable materials, persons, objects, and more particularly, but not limited, to the tracking of stolen articles, objects or missing persons through existing cellular network infrastructure, the global positioning system (GPS), WiFi networks, WiMax networks, and the like. The invention further relates to location and tracking systems and algorithms using a combination of directional vectors and signal strength estimates and location identifiers that are based on radio frequency transmissions. The invention also teaches a system for asset tracking that is less prone to render false positives so as to eliminate or lessen concerns for asset movements with acceptable or limited risks.
There are earlier location systems which make use of the constellation of global positioning satellites orbiting the earth. Such systems range from navigational aids to tracking devices. For example, there is a vehicle tracking and security system that allows immediate response in case of vehicle theft, an accident, vehicle breakdown, or other emergency. Guardian and tracking functions are provided through mobile units installed in hidden locations in vehicles to be monitored. The mobile units communicate with a control center. Preferably, the mobile unit provides vehicle theft and intrusion protection using an in-vehicle alarm and security system linked to the control center by a transceiver in the mobile unit. Also, a keypad or other human interface device is typically provided, allowing a vehicle driver or occupant to signal the control center that a particular type of assistance is needed. The vehicle's location may be automatically transmitted to the control center along with any automatic alarm signal or manually entered request, the location being precisely determinable anywhere in the world through use of Global Position System (GPS) information. The system provides continuous monitoring of a large number of vehicles for a broad range of status and emergency conditions over a virtually unlimited geographic area, also allowing manual communication of requests for assistance to that specific location.
Another example of the use of GPS to track the location of an automobile is an automatic vehicle location system that includes a radio positioning system receiver which receives GPS radio signals and includes a two-gimbaled gyroscope, which is used by a dead-reckoning positioning system. A controller determines position based upon the radio positioning system when the radio signals are available and upon dead-reckoning when the radio signals are not available. The dead-reckoning process is based upon a compensation factor, which is established in response to data received from the radio positioning system. The compensation factor acts as an adjustment to an inner gimbal angle to compensate for a minor drift away from level by the inner gimbal.
A further example is a method for detecting the position of a moving body in which the position of a moving body such as a vehicle can be detected with a high degree of precision. It is possible to perform data communication using radio waves between radio base stations and a vehicle capable of movement. Precise positions are stored in advance in the radio base stations. The radio base stations also include radio wave clocks that keep a common time. The radio base stations transmit radio waves containing this time information. The vehicle receives these radio waves and determines the difference between the received time information and the time provided by a clock in the vehicle, in order to detect the current position of the vehicle by calculating the distances between the vehicle and each of the radio base stations. Furthermore, it is also possible for the position of the mobile station to be calculated using a combination of information from the fixed station and information from GPS satellites. By employing this type of structure, it is possible to calculate the position of the mobile station even when it is not possible to calculate the position of the mobile station using the fixed stations alone or GPS satellites alone. Therefore, it is possible to find the position of the mobile station more accurately than when a conventional method is used.
There also exists a tracking device configured to resemble a stack of currency and represents a system for use in catching thieves. The device relates to the electronic tracking of cash stolen from a bank or other institution via an electronic signaling device placed within a stack of currency that transmits location information to the authorities as the cash is moved from location to location. The tracking device allows law enforcement officers to electronically monitor money stolen from a bank. The tracking device is sized to fit within a stack of currency in a teller's drawer or a bank's vault. When the tracking device is activated, it transmits a beacon signal that continuously runs for the duration of the battery. Thus, the tracking device would automatically send a signal to either fixed monitoring stations, such as antenna located on tall buildings, or to mobile monitoring stations, such as helicopters and/or police cars, allowing for continual tracking of the thief in possession of the stolen money. By knowing the location of the money, the police can track and apprehend the perpetrators. It is designed to be a circuit card smaller than a dollar bill and thin enough to be concealed between two sealed bills, thereby allowing it to be placed into a stack of money undetected. Further, the device is flexible and is able to be waterproofed, which will have no effect on its ability to be continually tracked, but would prevent someone from shorting out the device in liquid. Alternative embodiments allow variations of the tracking device to be placed within other objects of value. An alternative embodiment allows the tracking device to be automatically activated when it is taken past a certain point, e.g., an electronic fence, from where it is stored.
Furthermore, there are tracking systems for tracking the location of stolen articles, and more particularly, to disguised currency bundles for aiding law enforcement officials in apprehending thieves and recovering stolen monies. Such tracking is tracked by a tracking agency, which agency may work in concert with a law enforcement agency. In other situations, the functions of a tracking agency are undertaken by the law enforcement agency itself. Such system may include a security pack for assisting in the recovery of stolen monies, which includes a housing disguised as a bundle of currency bills, but containing a GPS receiver for receiving GPS signals from overhead satellites combined with a cellular phone transmitter (module), a microprocessor, antennae, and a battery. Following a bank robbery, the microprocessor activates the cellular phone transmitter to dial the telephone number of a central monitoring station. The microprocessor obtains location data from the GPS receiver and transmits the location data, along with identification information, to the central monitoring station. The security pack may also include a separate, conventional RF beacon transmitter for allowing authorities to home-in on the security pack within a large building or other structure, either after the GPS signals are lost, or after the location of the security pack is localized to a specific area or building.
All of the devices described above are implemented, or require for implementation, access to GPS or a custom radio network of receivers. This is an expensive requirement, increasing overall costs and the size of the devices. There is thus a need for a smaller, less expensive solution to tracking and aiding law enforcement officials in the recovery of lost or stolen articles or missing children while utilizing existing cellular telephone network infrastructure.